Device for detecting mechanical vibration.



F. GOTTSCHALK.

DEVICE FOR DETECTING MECHANICAL VIBRATION.

"APPLICATION FILED IAN.I5.'I9I4.

1 ,1 37,478. Patented Apr. 27, 1915.

3 SHEETS-SHEET I J z 6' 9 l F. GOTTSCHALK.

DEVICE FOR DETECTING MECHANlCAL VIBRATION.

APPLICATION FILED JAN- 15- 1914. 1 ,137 ,478, Patented Apr. 27, 1915.

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APPLICATION FILED JAN- 15, 1914.

Patented Apr. 27, 1915.

3 SHEETS-SHEET 3 FELIX GO'ETSCHALK, OF STIRLING, NEW JERSEY.

DEVICE FOR DETECTING MECHANICAL VIBRATION.

Specification of Il'..etters Patent.

Patented Apr. 2'7, 1915.

Application filed January 15, 1914. 7 Serial No. 812,266.

To all whom it may concern:

Be it known that I, FELIX GOTTSCHALK, a citizen of the United States,residing at Stirling, in the county of Morris and State of New Jersey,have invented certain new and useful Improvements in Devices forDetecting Mechanical Vibration, of which the following is aspecification, reference being had to the accompanying drawing.

My invention relates to means for electrically detecting mechanicalvibrations, such as the heart-beats of living things, minute relativemovements between parts of machines commonly referred to as knocks, andother localized vibrations. I obtain improved results by varying thecurrent fiow through my improved apparatus by the direct action ofmechanical vibrations. Others have heretofore attempted to achieve thisend through the medium of sound waves, as utilized in the usualtelephone transmitter or microphone, but the difficulties with suchdevices are such that they have a very limited fieldespecially when usedas stethoscopeswhereas my invention is especially adapted to such uses.

To more fully point out the advantages of my invention, it is necessaryto compare it with the usual form of microphonic telephone transmitter.The transmitter has a diaphragm adapted to collect the sound waves whichimpinge thereon. The mechanical movement of this diaphragm in turn actsupon a variable resistance medium, the changes in resistance of whichvary the current flowing, and thereby affect the diaphragm of a suitablereceiver. Such devices are first open to the serious objection that alarge portion of the force of the original mechanical vibration is lostin the air between the object and the transmitter diaphragm, and even ifthe diaphragm is placed in actual physical contact with the object,there are details of construction in all transmitters except mine thatwouldprevent them from receiving faint vibrations through mechanicalcontact. That there is a great loss in transferring the mechanicalvibrations to the instrument through the air, can be proven by placingmy device upon a table, with a watch or other device capable ofproducing regular and minute mechanical "ibrations. The watch may now bedrawn slowly away from my device to a distance of two or three feet, butthe vibrations will be entirely audible in the receiver of my device. Ifthe watch is now removed from the table so that the mechanicalvibratrons therefrom must pass through the air to reach my device, evena quarter of an inch air space will render the vibrations inaudible.

Should both the above experiments be repeated with the ordinarymicrophone transmitter it will be observed that same will operate withthe Watch in both positions, but best with the Watch nearest in eitherposit on, showing that it is sensitive to vibrations collected by itsdiaphragm, either from direct contact (inelfectually) or from the air(more efiectually), whereas my device is particularly susceptible todirect contact mechanical vibrations, and but slightly if at allaifected by sound vibrations passing between it and the object. It willalso be noted that, owing to my improved construction, adapted fordirect contact, the loss due to air-transferred is eliminated, while theextraneous noises always present and which are collected and magnifiedby the usual diaphragm microphone, are eliminated.

While my invention consists principally in the construction of thetransmitter, it also has the further objects of enabling the sound ofthe minute mechanical vibration to be considerably amplified in thereceiver by increasing the strength of the source of current without thedistortion, lack of clearness, or frying noises which attend suchprogedure when the usual microphone is use My construction also enablesa very compact and efficient stethoscope to be constructed, embracing asuitable battery, connections, transmitter, receiver and ear tubes.

As my transmitter construction alfords sufficient volume, a number ofreceivers may be connected in any suitable manner to the circuit andsatisfactory results secured. F or instance, at a surgical clinic, anumber of those present can listen at the same time to the heart beatsof the same patient, all receivers being operated by the sametransmitter and controlled by any suitable switching device located ineither the primary or secondary circuit.

To illustrate my invention, I will describe same as applied to aportable stethoscope as used by physicians, and to detect smallvibrations in machinery.

Figure 1 is a sectional View of the trans mitter. Fig. 2, a sectionalview of the vibratory member used in the transmitter. Fig. 3, a. frontView of the transmitter with the vibratory member removed, Fig. 4, aspecial form of receiver. Fig. 5, a side view in section of thereceiver. Fig. (3, a side view. of the battery case. Fig. 7, a frontView of the same. Fig. 8, a diagram of connections.

Like figures of reference denote the same parts wherever they are shown.

1 denotes the rear casing of the transmitter which supports the usualcell 2 carrying the two electrodes and variable resistance medium. Thecell is held in the casing 1,

by the nut 9. This structure can be varied within wide limits, and mayconsist of any well known form of transmitter cell. Interposed betweenthe rear casing 1 and the cell 2 is a metallic plate 3, which has anextension ear, forming the terminal 4 to which one of the circuit wiresmay be connected.

5 is a spider-shaped member connecting one of the cell-electrodesthefront one in this type of cell-with a plate-shaped vibratory member 6,which is carried solely by %he spider, having its outer edge entirelyree.

All of the foregoing parts are inclosed by a casing 7, which may have anaperture 8 at its front, although this is not strictly necessary.

10 is a wire connecting the front electrode,

the stem of which is shown at 11, with the terminal 12.

The weight of the vibratory member 6 and the shape of its flanged rim oredge,

varies with difl'erent cells, and may be pro portioned to meet variousrequirements. A weight alone on the front electrode will not sufiice,nor will a flat diaphragm,-especially if secured at its edge. Thepeculiar convex shape shown is necessary to produce the best results, asupon the vibrations of this member the efficiency of the device depends.I find it desirable in some cases to spin this member, so as to make themetal of which it is composed of a different thick ness at the centerand edge. It must be understood this member is not a sound receivingdiaphragm, but simply acts as a tuned amplifier or resonator in relationto the cell and the balance of the instrument.

The casing 7, or any part of the transmitter being placed in directcontact with the object to be observedfor instance the bearing 13,vibrations willpass from 13 to 7 to cell 2, and to the vibratory member6. The latter by reason of its property of amplification, reinforces andstrengthens these vibrations, thereby increasing the variable action ofthe transmitter cell 2, in the usual manner, on the current flowing. Thereceiver used with a transmitter of this description should possesscertain features, as shown in Figs. 4 and 5 to produce the maxi-' mumresults. 14 is a non-perforate cap, completely inclosing the front ofthe case 15 carrying" the coils, pole pieces and diaphragm 16, 17', and1-8. A U-shaped conduit is provided, as shown, to which is connected theusualear tubes 20 and 21. Suitable electrical connections, such as thecords 22 are provided. A receiver of this character is preferred by someto the usual double head receiver, and is of peculiar advantage whenused in connection with my improved transmitter as a stethoscope.

Figs. 6 and 7 show the preferred form of battery case. 22 is a casing,having a hook or other suitable member 23 whereby it may be hung up orpinned to the clothing. A terminal rack 24 is provided for the batterycells 25, the terminals 27 and 28 of which connect to the terminals 29and 30.on' the terminal rack, which are adapted to receive the ordinarypin connectors on the transmitter and receiver cords. Suitable holes 31in the outer casing are provided for the cord connectors.

The three pieces of apparatus just described, may be connected togetherin any suitable manner. Fig. 8 shows them connected in series. An extraterminal 32 may be mounted on the battery case to enable the transmitterand receiver cords to be joined. This arrangement makes a compact andeflicient light-weight stethoscope, and by having the socket terminalsof different sizes and the various pin-connectors to correspond, it isimpossible to improperly connect the apparatus.

I claim 1. In an apparatus of the character described, a transmittercell, a stem projecting from said cell, a vibratory member comprising aconcave plate shaped disk, having a rearwardly pro ecting flange carriedon said stem and a casing completely closing and surrounding said celland vibratory member and thereby shielding same from the direct actionof sound waves, substantially as described.

2. In an apparatus of the character described, a vibratory membercomprising a concave plate shaped disk having a rear wardly projectingflanged portion, a spider shaped member 5, the ends of which areattached to said vibratory member at interperipheral points on thelatter, and a resistance cell supporting said vibratory memher andspider, substantially as described.

3. In an apparatus of the character described, a vibratory member havinga flanged 5. In an apparatus of the character described, a vibratorymember having a curved surface in combination with a flanged edge, saidflange being substantially at right angles to the plane of the body ofsaid member.

6. In an apparatus of the character described, a diaphragm having acurved surface and an edge portion flanged at an angle to said surfaceand means for interperipherally mounting said diaphragm in a 10 freevibrating position.

In testimony whereof I hereunto affix my signature inthe presence of twoWitnesses.

FELIX GOTTSCHALK.

Witnesses CHAS. LUBRECHT,

W. J. LOWRIE.

